Input:
Output:
DILATE4 filter
The DILATE4 filter is a standard binary filter which works in a 3x3 environment.
The DILATE4 filter assigns a 1 to the center pixel if one or more horizontal or vertical neighbours are true as well; else a 0 is assigned.
The result of using DILATE4 is that true pixels 'grow' in horizontal and vertical direction.
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Input: |
Output: |
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Example 1:
When of 9 input pixels considered, all pixels in the lower row are true, and all others false (position 2 is a vertical true neighbour):
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0 |
0 |
0 |
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0 |
0 |
0 |
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1 |
1 |
1 |
The DILATE4 filter puts these pixel values in a special order or bit position as below (where 0 means last position, 1 one but last position, etc.):
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5 |
6 |
7 |
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4 |
8 |
0 |
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3 |
2 |
1 |
The ordering results in the following binary number : 000001110
(This equals: 21 + 22 + 23 = 2 + 4 + 8 = 14)
This number is looked up in a table which is present in the binary filter itself:
0-63=0101111101011111111111111111111101011111010111111111111111111111
.........
The value assigned to the center pixel is 1.
Example 2:
When only the lower left and lower right pixel are true (no horizontal or vertical true neighbours), like:
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0 |
0 |
0 |
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0 |
0 |
0 |
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1 |
0 |
1 |
the filter creates binary number: 000001010
(decimal: 21 + 23 = 2 + 8 = 10)
When answer 10 is looked up in the table; the output value is 0:
0-63=0101111101011111111111111111111101011111010111111111111111111111
........
See also: